Round balers have become quite prevalent for their capability of producing a conveniently sized cylindrical bale, very often automatically wrapped with a sheeting material such as net or film. Crop material, such as hay, is picked up from the ground as the baler travels across the field, and is fed into an expandable chamber where it is rolled up to form a compact cylindrical hay package.
Round balers generally have an expandable bale chamber defined by a pair of fixed sidewalls, and a plurality of side-by-side belts cooperating with a series of transverse rolls, mounted between a pair of pivotally mounted arms commonly known as a sledge. The chamber includes an inlet opening in the front through which crop material is fed. Also included is a pair of take up arms pivotally mounted on the main frame, between which arms multiple guide rolls are journalled. A biasing force is applied on the take up arms to urge the outer surfaces of the guide rolls against the belts to maintain belt tension and prevent slack from occurring in the belts during expansion and contraction of the chamber.
Modern round balers often sub-systems to monitor and control movement of the belts to produce bales of a desired size, shape uniformity, or density. Bale size monitoring is commonly accomplished through the use of potentiometers connected to the take up arms by mechanical linkages. As the bale grows in the chamber moving the take up arms, pivoting links transfer the take up arm movement to one or more potentiometers which produce an electrical signal indicative of bale size to the control/monitoring processor.
The signals indicative of bale size are frequently imprecise and can lead to problems in the baling cycle. Inherent free play in the linkage and flexure in the potentiometer mountings causes much of the imprecision. Linkages and/or potentiometers are easily damaged in the operating confines of the baler housing by contact with flying debris or nearby moving hydraulic hoses. The operating environment inside the baler housing is less than ideal for sensitive potentiometers which generally reduces their anticipated operating lifespan.
It would be desirable to provide a sensing apparatus that would provide a reliable indication of bale size based upon position of the take up arms. Additional advantages would be realized by a sensing apparatus that reduce the likelihood of bale size mis-indication due to damage or mal-adjustment of a mechanical linkage. Still further advantages would be realized by a bale size sensing apparatus that could be easily incorporated into existing round baler belt take up apparatus with minimal alteration of the existing baler.